In a reflector antenna[?], the relative reduction in the effective aperture of the antenna caused by the masking effect of other antenna parts, such as a feed horn or a secondary reflector, which parts obstruct the radiation path.
... Hepworth Museum[?], St. Ives, Cornwall
Penlee House, Penzance[?]
Tate St. Ives[?]
Cumbria
Abbot Hall Art Gallery[?], Kendal[?]
Beatrix Potter Gallery[?], ...